Regeneration of diesel particulate filter using nonthermal plasma without catalyst

Regulations regarding automotive diesel engine emissions become more severe every year, and it is difficult to meet the requirements with only combustion improvement techniques. More effective post-processing technology is desired especially for particulate matter (PM), such as carbon soots. Although the use of a ceramic diesel particulate filter (DPF) is now a leading technology for PM removal, the problem exists for the soot removal or regeneration at low temperature, especially at cold start. In the present study, a regeneration of a DPF with collected PM was investigated using the low-temperature atmospheric pressure nonthermal plasma. The method is to use the NO₂ and radicals induced by the plasma reactor to burn carbon soots deposited on the DPF. First, three types of DPF plasma reactors were made and the performance of the conversion of NO to NO₂ was evaluated at various conditions. Next, a regeneration experiment was carried out using a barrier-type pulse corona plasma reactor. As a result, it was confirmed that the pressure difference decreased when the plasma was turned on and the regeneration of the DPF (approximately 75% of soot removal) was confirmed when the gas temperature was 250°C.